The present invention relates to improvements in apparatus for testing rod-shaped articles which form part of or constitute smokers' products and wherein an open-ended tubular wrapper of cigarette paper, cork, reconstituted tobacco or the like surrounds a gas-permeable filler which consists of filter material and/or tobacco. More particularly, the invention relates to improvements in apparatus for the testing of rod-shaped articles in the form of plain or filter-tipped cigars, cigarettes, cigarillos or cheroots or sections of filter rods wherein the articles are moved sideways during transport toward, past and beyond one or more testing stations.
The wrappers of cigarettes or like rod-shaped articles (hereinafter referred to as cigarettes or filter cigarettes for short) are normally tested by a testing fluid which is admitted into or drawn from one or both ends of wrappers and whose pressure is monitored to detect such changes in pressure which are likely to develop when the wrapper has a hole, an open seam or another defect. A suitable transducer can be employed to produce signals which are indicative of cigarettes with defective wrappers, and such signals are utilized to effect segregation of corresponding cigarettes from satisfactory cigarettes. The rod-shaped articles to be tested may be of unit length (e.g., plain or filter cigarettes of unit length), of two times unit length (e.g., filter cigarettes of double unit length) or more than two times unit length (e.g., filter rod sections of four, six or eight times unit length). Presently utilized filter cigarette making machines normally produce filter cigarettes of double unit length and each such cigarette is thereupon severed midway between its ends to yield a pair of coaxial filter cigarettes of unit length. One filter cigarette of each pair is thereupon inverted end-for-end so that the filter plugs of all cigarettes face in the same direction. The cigarettes can be tested priot to and/or after severing. Testing subsequent to severing is preferred and more reliable because such mode of operation insures the detection of wrappers which become defective subsequent to or during severing. Moreover, filter cigarettes of unit length can be tested for the density of their filter tips and/or tobacco filler ends.
Many presently known testing apparatus employ a drum which is provided with axially parallel flutes for discrete cigarettes of unit length or multiple unit length and rotates with two coaxial carriers for sets of axially movable sealing tubes. The tubes move into sealing engagement with the adjacent ends of cigarettes prior to testing and are moved away upon completion of the testing operation so as to permit removal of tested articles and ejection of defective articles. Each tube normally comprises a follower which tracks the face of a stationary cam. Such means for moving the tubes are expensive and undergo extensive wear. Moreover, it is difficult to convert the just described testing apparatus for the testing of shorter or longer rod-shaped articles and/or for the testing of articles having larger or smaller diameters.
As stated before, the testing of cigarettes of unit length is normally preferred because such testing is more reliable since it insures the detection of defects which develop subsequent to severing of cigarettes of multiple unit length. Furthermore, if a cigarette of multiple unit length exhibits a defect in one of its sections (e.g., in one half of a filter cigarette of double unit length), the entire cigarette is discarded in spite of the fact that it could yield one or more satisfactory cigarettes plus one or more defective cigarettes. On the other hand, testing of cigarettes of unit length must be carried out at a high speed since a modern cigarette making machine can turn out up to and in excess of seventy articles per second. High-speed testing produces excessive wear on the moving parts of the testing apparatus so that there exists an urgent need for testing apparatus which are sufficiently reliable to allow for testing of extremely large numbers of articles per unit of time, especially for mass-testing of plain and filter cigarettes of unit length.